Drone & eVTOL Hover: Altitude, Cold Battery and Thrust Margin
Wired White v1 Check altitude and cold-weather hover using ISA density, rotor RPM, blade-loading and tip-Mach limits, battery voltage sag, thrust reserve and hover time.
#voltage-sag
Wired White v1 
Li-ion Voltage Under Load & Runtime: 2RC Cell Model
Wired White v1 Predict Li-ion cell voltage sag, cutoff time and usable capacity under constant, pulse or drive-style loads, with two RC transients and voltage relaxation.